Loom takeup let-back mechanism



11%? R. P. GUSTAFSON ETAL 3,332,453

LOOM TAKEUP LET-BACK MECHANISM 5 Sheets-Sheet 1 Filed July 12, 1965 INVENTOR RALPH P GUSTAFSON O$|AS J. LEBLANC BYu/Mo W4 ATTORNEY Filed July 12, 1965 R. P. GUSTAFSON ETAL LOOM TAKEUP LET-BACK MECHANISM 5 Sheets-Sheet 2 F l 6. BC] FCi B02 P02 803 Ah H TWO TEETH T ONE TOOTH C B ,C 5 I I; 'C f X D' ID INVENTOR RALPH P GUSTAFSON OSIAS J. LEBLANC ATTORNE jufiy 25, 196? R. P. GUSTAFSON ETAL LOOM TAKEUP LETBACK MECHANISM Filed July 12, 1965 5 Sheets-Sheet 5 F l G. 8 BTC FC FORWARD F PQ BKG ETC INVENTOR RA P GUSTAF N OS J. LEBLA BY MM M ATTORNEY United States Patent "ice 3,332,451 1.00M TAKEUP LET-BACK MECHANISM Ralph P. Gustafson, Hubbardstou, and Osias Joseph Le Blane, North Oxford, Mass, assignors to Crompton &

Knowles Corporation, Worcester, Mass, a corporation of Massachusetts Filed July 12, 1965, Ser. No. 471,361 7 Claims. (Cl. 139-313) This invention relates to let-back mechanism for loom takeup motions operated by a ratchet take-up mechanism in looms operating with electromagnetic clutch and brake assemblies like that shown in Patents Nos. 2,753,894 and 2,962,056.

Take-up motions of the ratchet tooth pick wheel type are usually actuated by some regularly moving part of the loom and receive an intermittent motion through a drive pawl to rotate the take-up roll in a steady forward direction. A hold pawl is usually employed to hold the pick wheel stationary while the drive pawl is in its backward stroke. When a fault in the filling occurs it is necessary for the weft to be withdrawn and unless the take-up roll is moved b'ackwardly an amount tocompensate for the withdrawn weft, a thin place will appear in the cloth. There have been various lift-out mechanisms to accompiish this let-back of the take-up roll which operate to disengage the pawls to allow the pick wheel to reverse due to the tension of the cloth. These lift-out mechanisms are actuated through a mechanical weft fault detector or starting handles commonly known as shipper handles. Mechanisms of this type are shown for instance in Patents Nos. 405,829, 748,262, 1,542,328, 2,185,063 and 2,591,- 538.

Looms of the type shown in the above mentioned Patents Nos. 2,753,894 and 2,962,056 which operate with an electromagnetic clutch and brake with electrical stopping and starting controls and including an electrical weft fault means to automatically stop the loom through the clutch and brake cannot make use of the previously mentioned let-back mechanisms.

One of the objects of the present invention is to provide a lift-out mechanism for the hold-pawl in the type of loom described which will operate from one of the driven shafts to lift the hold pawl out of engagement with the ratchet toothed pick wheel whenever the shaft is reversed, to permit let-back of the take-up roll.

Another object of the present invention is to provide a lift-out mechanism for the hold pawl for looms of the type described which are provided with a reverse electromagnetic clutch which automatically reverses the loom to the back center position after the loom has been brought to a stop at front center due to a weft fault, said lift-out pawl being effective to automatically lift the hold pawl out of engagement with the pick wheel during the reversing of the loom to allow limited let-back of the take-up roll.

Other objects and details of that which it is believed to be novel will be clear from the following description and claims taken with the accompanying drawings in which are illustrated examples of the present invention.

In the drawings:

FIGURE 1 is a fragmentary side elevation illustrating the preferred form of the invention.

FIGURES 2 and 3 are diagrammatic views illustrating the operation of a portion of the invention.

FIGURE 4 is a timing diagram relating to the preferred form of the invention.

FIGURE 5 illustrates a second embodiment of the invention.

FIGURE 6 illustrates a third embodiment of the invention.

3,332,45l Patented July 25, 1967 FIGURE 7 illustrates a fourth embodiment of the invention.

FIGURE 8 is a timing diagram relating to the fourth embodiment of the invention.

Referring to FIG. 1 there is shown 'a loom frame 10 with a top drive shaft 12 and a bottom shaft 1 Shaft 12 makes one rotation for each pick and shaft 14 makes one rotation for every two picks. Electromagnetic clutch and brake assembly along with the necessary gearing to drive shafts 12 and 14 are as shown in Patent No. 2,962,056. A ratchet tooth pick wheel 16 is fixedly mounted .on a shaft 18 on which the usual take-up roll (not shown) is mounted. A drive pawl generally indicated at 20 operates from a moving part of the loom in the usual manner to intermittently rotate the ratchet wheel 16 in the direction of arrow 22 while the loom is in operation. Turning of the ratchet wheel also turns the take-up rool to advance the cloth.

There is always a certain amount of tension on the cloth and consequently on the pick wheel. To keep ratchet Wheel 16 from turning back in the direction of arrow 24 when drive pawl 20 moves out of driving engagement with wheel 16 to pick up the next tooth, a hold pawl generally indicated at 26 is used to prevent the ratchet wheel from turning back. Hold pawl 26 pivoted at 25, has a holding tooth 23, and has an upwardly extending arm 27.

Pivoted at 30 on the frame 10 is a bell crank lever generally indicated at 28 with arms 32 and 34. Arm 34 abuts arm 27 at point 36. A second bell crank lever is pivoted at 40 on the frame 10 near shaft 14 and generally indicated at 38, has arms 41 and 42. Bell crank lever 38 is connected to lever 28 through an intermediate bell crank lever 43 and connecting rods 45 and 47. Pivoted at 44 to arm 41 is a member 46 normally biased against a stop 48 on lever 41 by a spring 50. Keyed to the shaft 14 is a cam member 52 with two projections 51, each with a sloping surface 54 on one side and a straight radial edge 55 on the other side.

When shaft 14 is running normally in the forward direction surfaces 54 strike surface 56 on member 46 due to the rotation of cam 52 in the direction of arrow 53 causing member 46 to move away from stop 48 in the direction of arrow 58, see FIG. 2. In the event of a weft fault upon which the shaft is stopped and then brought to back center position to remove the weft fault, cam 52 will be rotated in the direction of arrow 60. As the cam 52 rotates in this direction, the edges 55 of projection 51 will strike the member 46 at 62 causing bell crank lever 41 to rotate in a clockwise direction as viewed in FIG. 1, see also FIG. 3. By means of intermediate bell crank lever 43 and connecting rods 45 and 47 the rocking of lever 38 will cause lever 28 to rock in a counterclockwise direction causing hold pawl 26 to rock in clockwise direction around pivot 25 and lift out of engagement with the ratchet wheel 16.

Referring to FIG. 4 there is shown a timing diagram for the ratchet wheel 16 (as driven by the drive pawl), the hold pawl and the lift-out means. The horizontal dimension of the diagram is measured in terms of revolutions of the upper drive or crank shaft 12; BC indicates when the lay is at back center position and FC indicates when the lay is at front center position. The vertical dimension is measured in distance. Referring to the upper portion of the diagram, line A indicates the normal forward motion of the ratchet wheel 16 as it is advanced from back center to front center the distance of one tooth. There is a little over-travel to allow the hold pawl motion being indicated by line B, to drop into the vertex of the next tooth as indicated by arrow C. Line A from BC1 to FCl rep-resents a normal advance of the ratchet wheel 16, line A from BC2 to FC2 also represents an advance of wheel 16, but in this case a weft fault has occurred, causing the loom to stop at FC2 and then reverse. At this point cam 52 reverses and is so timed that it causes lever 38 to rock as shown in FIG. 3 and indicated by arrow D in FIG. 4. This lifts the hold pawl tooth 23 out of engagement with the tooth on the ratchet wheel 16 as indicated by arrow C As the loom reverses a little further, lever 38 turns to its normal position as indicated by arrow D At this point hold pawl 26 is free to drop but the ratchet wheel 16 has moved back just enough for the hold pawl to strike the top of the previously advanced tooth. Continued reversal of the loom to back-center position will allow ratchet wheel 16 to turn back the distance of one tooth, as drive pawl 20 reverses its stroke and allows the wheel to follow it back as indicated by broken line A until hold pawl 26 is again in holding relation with the ratchet wheel.

Referring to FIG. there is shown a modified form of hold pawl lift-out mechanism which operates in a manner similar to the mechanism shown in FIG. 1.

As shown in FIGURE 5 there is a hold pawl 62 pivoted at 64 with a holding tooth 66. Located near the cam 52 is a bell crank lever 68 pivoted at 70 with arms 72 and 73. Attached to arm 73 is a cord 74 which is trained around pulleys 76 and 78 and attached to the other end to pawl 62 at 79. Pivoted at 89 to arm 72 is a member 81 normally held against a stop 82 by a spring 83. When the 100m reverses due to a weft fault, lever 68 is rocked counter-clockwise, as viewed in FIG. 5, in the same manner as bell crank lever 38 which pulls the cord 74 in the direction of arrow 84 to lift tooth 66 of pawl 62 out of engagement with ratchet wheel 16.

In FIGURE 6 there is shown a second modified form of the invention. Located near the upper drive shaft 12 is a block 86 pivoted at 87 and held against a fixed struc ture 88 by a spring 89. Located in a hole 90 in block 86 is a compression spring 91 which supports a latch 92. Fixed to block 86 at 94 is a cord 96 which is trained around a pulley 97 and attached to a hold pawl 98 at 99.

Keyed or otherwise fixed to the shaft 12 is a cam 100 with a projection 102 which has an inclined surface 103 and a straight radial surface 104. Cam 100 is similar to cam 52 but has only one projection 102 because it makes one rotation for every pick as compared to two rotations for cam 52. The normal direction of rotation of cam 100 is opposite to the rotations of cam 52 as indicated by arrw 106. During normal operation, surface 103 of projection 102 contacts a surface 108 of latch 92 depressing same against spring 91. When the loom is reversed due to a weft fault, shaft 12 and cam 100 are turned in the direction of arrow 110 so that surface 104 strikes an edge 112 of latch 92 to rock block 86 around a pivot 87 which lifts pawl 98 out of engagement with pick wheel 16. The modified form just described is shown as being operated by a cam shaft 12 to illustrate that the various lift-out mechanisms shown herein can be adapted to be operated from either the top shaft 12 or the bottom shaft 14.

Referring to FIG. 7 there is shown a third modification, this one being also operated by a cam fixed to the shaft 12 and indicated by the reference numeral 113. Cam 113 has a high portion 114 which, during operation, moves a follower 116 to swing a lever 118 counter-clockwise as viewed in FIG. 7 around a pivot 120. This has the effect of lifting hold pawl 122 out of engagement with the pick wheel 16 once for every rotation of cam 113 or once for every pick. The mechanism is timed in such a way that this does not interfere with the advancement of the takeup mechanism during normal operation of the loom. When the loom is reversed however, pawl 122 is lifted at the correct time to allow let-back of the ratchet wheel. This timing is illustrated in FIGURE 8. Vertical lines BKC, BTC, FC, TC, etc. indicate the back center, bottom center, front center, top center, etc. of the loom crank shaft. In that figure line B represents the function of a hold pawl without any lift-out mechanism. Point G in FIGURE 8 represents the point in the loom cycle where the hold pawl drops to the base of the next tooth to be held and point H indicates the point where the hold pawl is actually holding the ratchet wheel. If the loom is reversed after point G the hold pawl will be engaged with the tooth and will prevent the ratchet wheel 16 from letting back. Line F represents the function of the hold pawl as operated by the mechanism shown in FIGURE '7. When the loom is running forward cam 113 is timed to lift the hold pawl out of engagement with wheel 16 before point G where it would normally have dropped to the base of a tooth and then lets it drop at point I in time to hold the wheel 16 at point K. When the loom is reversed the hold pawl will be lifted out of engagement with wheel 16 at point I and held out beyond point G which is where the hold pawl would normally begin to hold wheel 16 in the reverse direction.

By lifting out the hold pawl beyond point G it is then lowered on the top of a tooth and the ratchet wheel is allowed to let back the distance of one tooth. Although a ratchet wheel is advanced by the amount of one tooth per pick as shown, other ratchet wheels which have to be advanced by the amount of two or more teeth per pick could be used. Either the operating portions of the lift-out cam could be made so that the hold pawl is held out of engagement until just before the drive pawl has finished its driving stroke or multiple operating surfaces could be added to the cam.

As will be evident from the foregoing description, cer tain aspects of the invention are not limited to the particular details of construction of the example illustrated, and it is contemplated that various and other modifications of the invention will occur to those skilled in the art.

What is claimed and desired to be secured by Letters Patent of the United States is:

1. In a loom having a driven shaft, and a ratchet driven fabric takeup comprising a pick wheel, a drive pawl, and a hold pawl, means to selectively disengage said hold pawl, comprising:

(a) a cam fixed to said driven shaft for rotation therewith; and

(b) means operated by said cam to disengage said hold pawl from said pick wheel to permit said takeup to let back only when said shaft is driven in a direction opposite to its normal direction of rotation.

2. In a loom as set forth in claim 1 wherein the means operated by the cam comprises a spring biased member which yields when said shaft is driven in its normal direction but is acted on by said cam when said shaft is driven in the opposite direction to disengage said hold pawl.

3. In a loom as set forth in claim 1 wherein the hold pawl is disengaged to permit said takeup to let back a selected amount for each revolution of said shaft in said opposite direction.

4. In a loom as set forth in claim 1 wherein the means operated by said cam comprises:

(a) a pivoted lever disposed adjacent said cam;

(b) linkage means operatively connecting said hold pawl with said pivoted lever; and

(c) a spring biased member disposed on said lever and extending into the path of a portion of said cam whereby said member will yield when said shaft is driven in its normal direction and will cause said lever to pivot only when said shaft is driven in the opposite direction to permit the takeup to let back a selected amount.

5. In a loom as set forth in claim 4 wherein said lever is a bell crank and the linkage means is attached to one of its ends and the spring biased member is disposed on the other end of said lever.

3,332,451 5 6 6. In a loom as set forth in claim 1 wherein the means References Cited operated by said cam comprises a pivoted lever having UNITED STATES PATENTS one end connected to said hold pawl and the other end 2,591,538 4/1952 Gosnell 139-313 extending into the path of a portlon of said cam when 2 611396 9/1952 Rinne et a1 the hold pawl is in engagement with said pick wheel. 5 2962056 11/1960 Paul et a1 7. In a loom as set forth in claim 6 wherein said cam FOREIGN P is timed so as to permit said takeup to let back when said shaft is driven in a direction opposite to its normal direc- 1391952 4/1903 Germanytion of rotation but not to interfere with the normal opera- 4841164 10/ 1929 Germanytion of the fabric takeup when said shaft is being driven 10 MERVIN STEIN, Primary Examiner. in its normal dlrection- T. KEE CHI, Assistant Examiner. 

1. IN A LOOM HAVING A DRIVEN SHAFT, AND A RATCHET DRIVEN FABRIC TAKEUP COMPRISING A PICK WHEEL, A DRIVE PAWL, AND A HOLD PAWL, MEANS TO SELECTIVELY DISENGAGE SAID HOLD PAWL, COMPRISING: (A) A CAM FIXED TO SAID DRIVEN SHAFT FOR ROTATION THEREWITH; AND (B) MEANS OPERATED BY SAID CAM TO DISENGAGE SAID HOLD PAWL FROM SAID PICK WHEEL TO PERMIT SAID TAKEUP 